1. Field of the Invention
The invention relates to an electroacoustic transducer with a membrane, the membrane having a membrane axis and a ring-shaped pleats area in which a multitude of pleats is provided.
The invention also relates to a membrane for an electroacoustic transducer, the membrane having a membrane axis and a ring-shaped pleats area in which a multitude of pleats is provided.
2. Description of the Related Art
An electroacoustic transducer corresponding to the aforesaid embodiment described in the first paragraph, and a membrane corresponding to the aforesaid embodiment described in the second paragraph, are known, for example, from U.S. Pat. No. 6,038,327. In the solution known from the above-referenced patent, the pleats provided in the pleats area have an identical design throughout the pleats area, i.e., the same mechanical design conditions always recur continually. In other words, this means that all pleats are in conformity with each other with regard to the pleat parameters and, in the known solution, have the same pleat dimensions (length, breadth, depth) and the same pleat cross-sectional shape, namely, essentially a V-shaped pleat cross-sectional shape, and the same pleat pattern, namely, a rectilinear pleat pattern, and the same pleat location in relation to the membrane axis, namely, an almost tangential pleat location. With the known transducer, unfortunately, there is the problem that interference effects on the membrane, which could be caused, for example, due to the fact that non-uniform attaching conditions occur when the membrane is attached to the transducer housing, for example, due to non-uniform adhesive distribution, at certain frequencies could result in unwanted oscillations in the membrane with the result that the oscillating part of the membrane for the generation of sound is no longer oscillated sufficiently precisely parallel to the membrane axis, but an unwanted disruptive movement occurs, generally involving an essentially slewing motion around a swivel axis transverse to and sometimes even exactly perpendicular to the transducer axis, the result of which is that the oscillator coil connected to the membrane does not perform the required movement precisely parallel to the membrane axis, but a movement deviating from this required movement which may have the result that the oscillator coil unfortunately strike parts of the known transducer""s magnet system which is closely adjacent to the oscillator coil. In the known transducer, the occurrence of this kind of unwanted disruptive movement may be prevented by feeding less electrical energy to the oscillator coil, but this, in turn, has the drawback that the acoustic energy achievable with the transducer can only be relatively low, so that only a relatively low and, in many applications, for example, in so-called speakerphones, unsatisfactory sound reproduction may be achieved.
It is the object of the invention to remove the aforesaid problems and develop an improved transducer and an improved membrane.
To achieve the aforesaid object, an electroacoustic transducer is provided with features according to the invention so that an electroacoustic transducer according to the invention may be characterized in the way described below, namely:
An electroacoustic transducer with a membrane, the membrane has a membrane axis and a ring-shaped pleats area, the pleats area being provided with a multitude of pleats, diametrically opposed pleats being embodied differently with regard to a least one of the pleat parameters.
To achieve the aforesaid object, in addition a membrane is provided with features according to the invention so that a membrane according to the invention may be characterized in the way described below, namely:
A membrane for an electroacoustic transducer, the membrane having a membrane axis and a ring-shaped pleats area, a multitude of pleats being provided in the pleats area, diametrically opposed pleats being embodied differently with regard to at least one of the pleat parameters.
The provision of the features according to the invention is a structurally extremely simple way, involving virtually no additional expense, of achieving the object that in a membrane according to the invention for an electroacoustic transducer according to the invention, identical structural relationships in diametrically opposed areas relative to the membrane in the ring-shaped pleats area are deliberately avoided, the result of which is that the formation of a disruptive movement around one or more axes running transverse to or perpendicular to the transducer axis, is counteracted to such a degree that, if there are any at all, only disruptive movements with a very low amplitude can occur and will entail virtually no detrimental consequences, because no unwanted or detrimental impact of the oscillator coil in a transducer according to the invention on the parts of the magnet system surrounding the oscillator coil can take place. This has the advantage that significantly more electrical energy may be fed to the oscillator coil in a transducer according to the invention as compared with the transducer known from U.S. Pat. No. 6,038,327, which advantageously has the consequence that the sound energy (electrical energy) which may be generated with a transducer in accordance with the invention, is much higher and, hence, a much louder sound reproduction may be achieved with a transducer according to the invention.
In a transducer according to the invention, it has been found to be very advantageous if the ring-shaped pleats area is subdivided into ring sectors. Here it has been found to be particularly advantageous, if the ring sectors extend through equally large angular areas. This is a way to achieve a very good suppression of unwanted disruptive movements. As the result of the fact that in a transducer according to the invention, diametrically opposed pleats are always embodied differently with regard to at least one of the pleat parameters, there is always an odd number of ring sectors.
In a transducer according to the invention, in which the ring-shaped pleats area is subdivided into an odd number of ring sectors, there may be five, seven, or even more such ring sectors. However, it has been found to be particularly advantageous if only three ring sectors are provided, each extending through an angular area of 120xc2x0. An embodiment of this type has been found to be particularly efficient in tests.
In a transducer according to the invention, the pleats may, for example, have a spiral pattern, which has been known per se for a long time. However, it has been found to be particularly advantageous, if the features, in which the pleat in the middle of a ring sector run linearly in a radial direction, and all other pleats in a ring sector run parallel to the pleat lying in the center of a ring sector and running in a radial direction, are also provided in a transducer according to the invention. An embodiment of this type is characterized by a particularly good acoustic behavior. In addition, an embodiment of this type is characterized in that a particularly good suppression of disruptive movements may be achieved.
With an embodiment of an electroacoustic transducer according to the invention as described in the previous paragraph, it has been found to be particularly advantageous if the features, in which, in every transitional area between two ring sectors, at least one essentially V-shaped transitional pleat is provided of which every pleat limb runs parallel to the adjacent linearly running pleat, are also provided. V-shaped transitional pleats achieve the advantage that sufficient membrane softness is guaranteed in the transitional areas between the ring sectors of the ring-shaped pleats area, which is favorable for good acoustic properties.
The aforesaid advantages in connection with an electroacoustic transducer according to the invention, also apply analogically to a membrane according to the invention.
The aforesaid aspects and further aspects of the invention may be derived from the following examples of embodiments and are described with reference to these examples of embodiments.